# Final Plan Summary: Where Guard Preprocessor Bug Fix

## Approach
Five-step implementation: (1) Fix nested pattern detection by removing `&& !hasGuards` condition, (2) Add 2-level depth validation with new helper functions, (3) Implement multi-level guard support for both outer and inner patterns with if-else-if chains, (4) Create new simple test `pattern_match_13_nested_guards_simple.dingo` for regression prevention, (5) Validate all 104 tests pass.

## Key Technical Decisions
- Multi-level guard support: Distinguish outer vs inner guards via binding analysis (references innermost binding → inner, otherwise → outer)
- Depth validation: Paren-counting algorithm enforces 2-level maximum with clear error messages
- Code generation: Reuse existing guard chain pattern (if-else-if) adapted for nested switches with careful indentation tracking

## Implementation Complexity
Medium-High: ~150 lines across 6 new helper functions, 3.5 hours implementation + 1 hour testing. Core changes in `rust_match.go:generateCaseWithGuards` (lines 773-981), particularly nested pattern case generation (lines 836-883).

## Expected Outcome
Test count: 102/103 → 104/104 passing. Fixes `pattern_match_06_guards_nested`, adds `pattern_match_13_nested_guards_simple`, maintains all existing functionality with zero regressions.
